JP2020115157A - Light reflection film and manufacturing method for light reflection film - Google Patents

Abstract

To provide a light reflection film excellent in flatness, adhesion and light reflection, and also excellent in durability, and a manufacturing method thereof.SOLUTION: A light reflection film 1 has a pair of base material films 2A and 2B, and two or more reflection layer units in which two or more layers having different refractive indices are laminated, wherein an adhesive layer AL is provided between the two or more reflection layer units, a layer thickness of the adhesive layer AL is within a range of 0.1 to 1.0 μm, and a reflection layer unit group composed of the two or more reflection layer units and the adhesive layer AL is sandwiched by the pair of base material films 2A and 2B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light-reflecting film and a method for producing a light-reflecting film, and more particularly to a light-reflecting film having excellent flatness, adhesiveness and light-reflecting property, and excellent durability, and a method for producing the same.

In recent years, interest in energy conservation measures has increased, and in building window glass and vehicle window glass, infrared radiation is used for the purpose of shielding solar radiant energy entering the interior or interior of a vehicle, reducing the temperature rise in the interior or interior of the vehicle, and reducing the cooling load. An insulating glass having a shielding property is adopted. In addition, a method of attaching a light reflection film formed by laminating layers having different refractive indexes to a window glass to block the transmission of heat rays in sunlight has attracted attention as a simpler method.

As a method for producing such a light reflection film, as a technique using a liquid phase film forming method, for example, in Patent Document 1, a coating solution containing a mixture of a water-soluble polymer and metal oxide fine particles is wet coated. A light-reflecting film (near-infrared reflecting film) manufactured by coating and laminating by a method is disclosed. According to Patent Document 1, a coating liquid containing zirconium oxide is prepared as a coating liquid for a high refractive index layer, and a coating liquid containing a low refractive index oxide such as silicon oxide is prepared as a coating liquid for a low refractive index layer. A method of coating to form a laminated film is described, and it is said that an inexpensive and high-performance light reflecting film can be produced by this method.

However, in the method described in Patent Document 1, it was found that when the number of layers formed by multi-layer coating is increased, strong curl and decrease in adhesion of the multi-layer multilayer film occur as the coating film thickness increases. did. Since the curl is strong, there is a problem that it is difficult to attach the light reflection film to a substrate such as a window glass, and further, there is a problem in that the light reflection film is peeled from the end portion when it is stored for a long period of time.

On the other hand, as a method for preventing curling in a laminate having a multilayer film, for example, in Patent Document 2, in a gas barrier film field having a gas barrier layer having a multilayer structure, a gas barrier layer having the same structure is used. There is disclosed a gas barrier film having a structure in which two gas films having the respective gas barrier layers are arranged to face each other and are laminated via an adhesive layer. With this structure, it is said that it is possible to prevent problems due to curling and prevent damage to the gas barrier layer.

However, the invention described in Patent Document 2 is directed to a gas barrier film, has a different application field from the light reflection film, and the gas barrier layer in contact with the adhesive layer has a single-layer structure, and has a plurality of layers. There is no disclosure regarding the problems relating to the laminated body in which the above are laminated.

Further, Patent Document 3 proposes a multilayer film having a configuration in which two laminates in which a thermoplastic resin layer and an adhesive resin layer are alternately laminated between an outer layer and an inner layer are laminated with an adhesive layer in between. Has been done. It is said that such a structure can prevent curling. However, the method described in Patent Document 3 is for skin pack packaging, has a different application field from the light reflection film targeted by the present invention, and does not involve any problems in the configuration in which the optical reflection layers are laminated. Is not mentioned.

Japanese Patent No. 5147034 JP, 2011-121347, A JP, 2016-155297, A

The present invention has been made in view of the above problems and circumstances, and a problem to be solved is to provide a light-reflecting film having excellent flatness, adhesion and light reflectivity, and excellent durability, and a method for producing the same. It is to be.

MEANS TO SOLVE THE PROBLEM As a result of investigating the cause of the said problem in order to solve the said subject, a pair of base film and two or more reflective layer units in which two or more layers with a different refractive index were laminated|stacked are provided. A reflective layer unit group having an adhesive layer between the two or more reflective layer units, having a layer thickness of the adhesive layer within a specific range, and including the two or more reflective layer units and the adhesive layer. However, it has been found that the light reflection film sandwiched between the pair of base material films can realize a light reflection film having excellent flatness, adhesiveness and light reflectivity, and excellent durability. Came to.

That is, the above-mentioned subject concerning the present invention is solved by the following means.

1. A light reflection film having a pair of base material films and two or more reflection layer units in which two or more layers having different refractive indexes are laminated,
An adhesive layer is provided between the two or more reflective layer units, and the layer thickness of the adhesive layer is within a range of 0.1 to 1.0 μm,
A light reflection film, wherein a reflection layer unit group composed of the two or more reflection layer units and an adhesive layer is sandwiched between the pair of base material films.

2. In the configuration having the two or more reflective layer units, when the number of layers of one reflective layer unit facing each other with the adhesive layer in between is L1 and the number of layers of the other reflective layer unit is L2, each reflective layer unit The value L1/L2 of the ratio of the number of layers is in the range of 0.5 to 1.5, The light-reflecting film as described in the above item 1.

3. One of said pair of base material films is a transfer film which can be peeled off, The light reflection film of Claim 1 or 2 characterized by the above-mentioned.

4. The content of the inorganic fine particles in the adhesive layer is in the range of 0 to 20% by volume, The light reflection film as described in any one of the items 1 to 3.

5. A method for producing a light-reflecting film for producing the light-reflecting film as described in any one of items 1 to 4,
A method for producing a light reflecting film, comprising using two or more film units having a reflecting layer unit on a base film, and bonding the two reflecting layer units via an adhesive layer.

6. When bonding at least two film units, one film unit has a transfer film that can be peeled as a base film, and after peeling the transfer film, it is bonded to the other film unit via an adhesive layer. The method for producing a light-reflecting film as described in the item 5, further comprising:

By the above means of the present invention, it is possible to provide a light-reflecting film having excellent flatness and adhesiveness and excellent durability, and a method for producing the same.

Although the mechanism of action and mechanism of action of the present invention have not been clarified, it is presumed as follows.

For example, in the method described in Patent Document 1, when the number of layers is increased by multilayer coating, a strong curl and a decrease in the adhesiveness of the multilayer laminated film may occur due to the effect of increasing the coating film thickness. .. In addition, since the curl of the light-reflecting film becomes strong, it is difficult to attach the light-reflecting film to a substrate such as glass for buildings and glass for vehicles, and there is a problem of poor trackability, and in addition, for a long time in various environments. There was a problem that peeling occurred from the edges when stored.

The present inventors do not use a method of forming a reflective layer group in which two or more layers each having a different refractive index are laminated by one coating, but a reflective unit having a smaller number of layers than a desired number of layers. It was found that the above-mentioned problems can be solved by forming the above and bonding them with an adhesive layer having a thin layer thickness, and completed the present invention.

Since the reflective layer unit formed with a small number of layers has a small curl, handling or peeling does not occur. By bonding a plurality of reflective layer units with an adhesive layer having a coherence distance of 1 μm or less, the two reflective layer units interfere with each other, resulting in sharpness (narrow half width) and high reflectance. I found that. Further, it was found that by regulating the concentration of the inorganic fine particles in the adhesive layer to 20% by volume or less, the stress of the reflective layer unit group was relaxed, and the adhesion and durability were further improved.

Schematic sectional view showing a first example of the configuration of the light-reflecting film of the present invention. Schematic sectional view showing a second example of the configuration of the light-reflecting film of the present invention. Schematic sectional drawing which shows the 3rd example (laminate) of the structure of the light reflection film of this invention. Schematic which shows the process step which manufactures a 2nd example using the laminated body shown in FIG. Schematic which shows an example of the manufacturing method of the light reflection film of this invention. The graph which shows an example of the reflection spectrum of the light reflection film of this invention. The graph which shows an example of the reflection spectrum of the light reflection film of a comparative example.

The light reflecting film of the present invention is a light reflecting film having a pair of base material films and two or more reflecting layer units in which two or more layers having different refractive indexes are laminated, and the two or more reflecting layers. An adhesive layer is provided between the units, the layer thickness of the adhesive layer is within a range of 0.1 to 1.0 μm, and the reflective layer unit group composed of the two or more reflective layer units and the adhesive layer is It is characterized by being sandwiched between the pair of base material films. This feature is a technical feature common to the inventions according to each claim.

In the light-reflecting film of the present invention, from the viewpoint that the effect of the present invention can be more effectively expressed, in a structure having the two or more reflecting layer units, the layers of one reflecting layer unit facing each other with the adhesive layer sandwiched therebetween. When the number is L1 and the number of layers of the other reflecting layer unit is L2, it is more preferable that the ratio value L1/L2 of the number of layers of each reflecting layer unit is within the range of 0.5 to 1.5. It is preferable in that excellent reflection characteristics can be obtained.

Further, it is preferable that one of the pair of base material films is a transfer film that can be peeled off, because the thickness of the entire light reflection film can be reduced.

Further, it is preferable that the adhesive layer contains the inorganic fine particles within the range of 0 to 20% by volume from the viewpoint of stress relaxation and durability improvement of the reflective layer unit.

In addition, in the method for producing a light-reflecting film of the present invention, it is necessary to use two or more film units each having a reflective layer unit on a base film, and to bond the two reflective layer units via an adhesive layer. Is characterized by.

Moreover, when bonding at least two said film units, one film unit has a transfer film which can be peeled as a base film, and after peeling the said transfer film, the other film unit via an adhesive layer. It is a preferable embodiment to have a step of laminating with the point that a light reflecting film having a configuration having three or more reflecting layer units can be efficiently produced via a plurality of adhesive layers.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" showing a numerical range is used in the meaning including the numerical value described before and after that as a lower limit and an upper limit.

<<Basic structure of light reflection film>>
The light reflection film of the present invention has a pair of base film and two or more reflection layer units in which two or more layers having different refractive indexes are laminated, and an adhesive layer between the two or more reflection layer units. And a layer thickness of the adhesive layer is within a range of 0.1 to 1.0 μm, and the reflective layer unit group composed of the two or more reflective layer units and the adhesive layer has the pair of bases. It is characterized in that it is sandwiched between material films.

Hereinafter, a typical configuration example of the light reflecting film of the present invention will be described with reference to the drawings. However, the present invention is not limited to the configuration illustrated here. In the description of each drawing, the numbers in parentheses at the end of the constituent elements represent the reference numerals in each drawing.

(First configuration example of the light reflecting film)
First, an example of a light reflecting film having a basic structure having two reflecting units will be described.

FIG. 1 is a schematic cross-sectional view showing a first example of the configuration of the light reflecting film of the present invention.

As shown in FIG. 1, the first example of the light-reflecting film (1) of the present invention is at a position in contact with a base film 1 (2A, for example, a transparent resin film of polyethylene terephthalate (abbreviation: PET), etc.), A first reflective layer unit (3A) is formed. This is called the first film unit (F1). The first reflective layer unit (3A) is configured by laminating two or more layers having different refractive indexes. Specifically, the high refractive index layers and the low refractive index layers are alternately laminated. It is a laminated body.

On the other hand, the second reflective layer unit (3B) is also formed on the base film 2 (2B) which is the other of the pair of base films. This is called the second film unit (F2).

The first film unit (F1) on the one hand and the second film unit (F2) on the other hand are in contact with the respective reflection layer units, and the adhesive layer (AL) is arranged to arrange the light reflection film (1). I am configuring.

In the present invention, the two or more reflective layer units in which two or more layers having different refractive indexes are laminated may be reflective layer units having the same configuration or reflective layer units having different configurations. ..

In the present invention, a laminated body constituted by laminating two or more layers having different refractive indexes is referred to as a "reflection layer unit", and is constituted by two or more reflection layer units and an adhesive layer provided between them. Those that are referred to as "reflection layer unit group".

<Reflective layer unit>
The reflective layer unit according to the present invention is preferably a laminated body in which a high refractive index layer and a low refractive index layer are alternately laminated, but a "high refractive index layer" and a "low refractive index layer". The term means that, when the refractive index difference between two adjacent layers is compared, the higher refractive index layer is the high refractive index layer and the lower refractive index layer is the low refractive index layer. To do. Therefore, the terms "high refractive index layer" and "low refractive index layer" are the same in the respective refractive index layers constituting the light-reflecting film when the two adjacent refractive index layers are focused. It includes all forms other than the form having a refractive index.

(Second configuration example of light reflecting film)
FIG. 2 is a schematic cross-sectional view showing a second example of the configuration of the light reflecting film of the present invention, in which three reflective layer units and an adhesive layer is provided on each reflective interlayer unit.

In FIG. 2, a first reflective layer unit (3A), an adhesive layer 1 (AL1), and a second reflective layer unit (3B) are provided between a pair of base film 1 (2A) and base film 2 (2B). , The adhesive layer 2 (AL2) and the third reflective layer unit (3C) are arranged.

In the present invention, in a configuration having two or more reflective layer units, when the number of layers of one reflective layer unit facing each other with the adhesive layer sandwiched is L1 and the number of layers of the other reflective layer unit is L2, It is a preferred embodiment that the ratio value L1/L2 of the number of layers of the reflective layer unit is in the range of 0.5 to 1.5.

In FIG. 2, the reflective layer units located at the positions facing each other with the adhesive layer sandwiched therebetween refer to the first reflective layer unit (3A) and the second reflective layer unit (3B) disposed with the adhesive layer 1 (AL1) in between. ), and when the number of layers is L1 and L2, respectively, it is preferable that L1/L2=0.5 to 1.5. Similarly, it is arranged with the adhesive layer 2 (AL2) interposed therebetween. Also in the 2nd reflective layer unit (3B) and the 3rd reflective layer unit (3C) which exist, when the number of each layer is set to L2 and L3, it may be in the range of L2/L3=0.5-1.5. preferable.

(Third configuration example of the light reflecting film)
FIG. 3 is a third example of the configuration of the light reflecting film of the present invention, and is a schematic cross-sectional view showing a configuration in which one of the pair of base film is a peelable transfer film.

Further, the light reflecting film shown in FIG. 3 is effective for manufacturing the second example of the structure of the light reflecting film of the present invention. The laminate shown in FIG. 3 can be effectively used, for example, as an intermediate when producing the light reflection film shown in FIG.

The laminate (1A) having the structure shown in FIG. 3 is similar to the structure described in FIG. 1, but when the light reflection film having the structure shown in FIG. 2 is produced, the laminate (1A) is formed on the base film 2 (2B). The third reflection layer unit (3C), the adhesive layer 2 (AL2), the second reflection layer unit (3B), and the peelable transfer film (5) as the outermost layer.

Hereinafter, with reference to FIG. 4, the outline of the process steps for producing the light reflection film having the configuration shown in FIG. 2 using the laminate (1A) having the transfer film (5) shown in FIG. 3 will be described.

FIG. 4 is a schematic diagram showing process steps for producing the light reflecting film having the configuration of the second example shown in FIG. 2 using the laminated body shown in FIG.

(1) In step (1), the third reflective layer unit (3C) is formed on the base film 2 (2B).

(2) In step (2), the adhesive layer 2 (AL2) is formed on the third reflective layer unit (3C).

(3) In step (3), the second reflective layer unit (3B) is formed on the transfer film (5), and the adhesive layer 2 (AL2) and the second reflective layer unit (3B) are arranged to face each other.

(4) In step (4), the adhesive layer 2 (AL2) and the second reflective layer unit (3B) are attached to each other by the method shown in FIG. 5 described later to produce a laminate (1A).

(5) In step (5), the transfer film (5) is peeled off from the laminate (1A) to form the second film unit (F2).

(6) In step (6), the second film unit (F2) and the first film unit (F1) having the first reflective layer unit (3A) formed on the base film 1 (2A) will be described later. The light reflecting film (1) is produced by laminating it via the adhesive layer by the method shown in FIG.

The light-reflecting film having the transfer film shown in FIG. 3 can be used as a single light-reflecting film, and when the light-reflecting film is provided with the transfer film (5), the light-reflecting film can be used at the manufacturing stage. The transfer film (5) prevents damage such as scratches to each reflection layer unit, and when used as a light reflection film, for example, the transfer film (5) is peeled to obtain a thinner light reflection film. This is preferable because as a result, it is possible to enhance the curved surface followability with respect to the vehicle glass having a curved surface or the like.

<<Constituent material of light reflection film>>
[Base film]
The substrate used in the light reflecting film of the present invention is not particularly limited as long as it is formed of a transparent organic material.

Examples of the substrate applicable to the substrate film according to the present invention include methacrylic acid ester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate, polystyrene (PS), aromatic Examples thereof include films made of resins such as polyamide, polyether ether ketone, polysulfone, polyether sulfone, polyimide, and polyetherimide, and resin films formed by laminating two or more layers of the above resins. From the viewpoint of cost and availability, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC) and the like are preferably used.

The thickness of the base film is preferably about 5 to 200 μm, more preferably 15 to 150 μm. The substrate may be a laminate of two or more sheets, and in this case, the type of the substrate may be the same or different.

Further, the substrate film preferably has a transmittance in the visible light region shown in JIS R 3106:1998 of 85% or more, and particularly preferably 90% or more. When the base material has the above transmittance or more, it is advantageous and preferable in that the transmittance in the visible light region shown in JIS R 3106:1998 when it is used as a light reflecting film is 50% or more.

Further, the base film using the resin or the like may be an unstretched film or a stretched film. A stretched film is preferable from the viewpoint of improving strength and suppressing thermal expansion.

The base film can be manufactured by a conventionally known general method. For example, a resin as a material is melted by an extruder, extruded by an annular die or a T-die, and rapidly cooled to produce a substantially amorphous and unoriented unstretched substrate. Further, the unstretched substrate is uniaxially stretched, tenter type sequential biaxial stretching, tenter type simultaneous biaxial stretching, tubular type simultaneous biaxial stretching, and the like, by a known method such as the flow direction (vertical axis) of the substrate, or A stretched base material can be manufactured by stretching in a direction perpendicular to the flow direction of the base material (horizontal axis). The draw ratio in this case can be appropriately selected according to the resin as the raw material of the base material, but is preferably 2 to 10 times in each of the vertical axis direction and the horizontal axis direction.

Further, the base film may be subjected to a relaxation treatment or an off-line heat treatment in terms of dimensional stability. The relaxation treatment is preferably performed in the step of heat-setting during the stretch-forming step of the polyester film, and then in the step of transversely stretching the tenter, or in the step of winding after exiting the tenter. The relaxation treatment is preferably carried out at a treatment temperature of 80 to 200°C, more preferably 100 to 180°C. In addition, the relaxation rate is preferably in the range of 0.1 to 10% in both the longitudinal direction and the width direction, and more preferably the relaxation rate is 2 to 6%. By subjecting the relaxed base material to the following off-line heat treatment, the heat resistance is improved and the dimensional stability is improved.

The substrate film is preferably coated inline with the undercoat layer coating liquid on one or both surfaces during the film formation process. In the present invention, the undercoat coating in the film forming process is called in-line undercoating. Examples of the resin used in the undercoat layer coating liquid useful in the present invention include polyester resin, acrylic modified polyester resin, polyurethane resin, acrylic resin, vinyl resin, vinylidene chloride resin, polyethyleneimine vinylidene resin, polyethyleneimine resin, polyvinyl alcohol resin. , Modified polyvinyl alcohol resin, gelatin, and the like, and any of them can be preferably used. Conventionally known additives may be added to these undercoat layers. The undercoat layer can be coated by a known method such as roll coating, gravure coating, knife coating, dip coating or spray coating. The coating amount of the undercoat layer is preferably about 0.01 to ² g/m ² (dry state).

<Transfer film>
In the present invention, it is preferable that one of the pair of substrate films is composed of a peelable transfer film.

The transfer film is a reflection of a substrate film applicable to the present invention described above, for example, a substrate film made of a resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or polycarbonate (PC). A film having a release layer having a release agent formed on the surface side in contact with the layer unit, and examples of the release agent include silicone-based resins, long-chain alkyl-based resins, fluorine-based resins, fluorosilicone resins, long-chain alkyl-modified Examples thereof include alkyd resins such as alkyd resins and silicone-modified alkyd resins, and a release agent composed of a silicone resin is preferable. The silicone contained in the release agent is a monofunctional silicone (a structural unit having three organic substituents), a bifunctional silicone (a structural unit having two organic substituents), and a trifunctional silicone (one organic substituent). It is preferable to include a structural unit having one unit) and a tetrafunctional silicone (a structural unit having no organic substituent).

[Main constituent materials of reflective layer unit]
The light reflecting film of the present invention is characterized by having two or more reflecting layer units in which two or more layers having different refractive indexes are laminated with an adhesive layer interposed therebetween.

The reflective layer unit is configured by laminating two or more layers having different refractive indexes, and is specifically a laminated body in which high refractive index layers and low refractive index layers are alternately laminated.

In the present invention, the two or more reflective layer units in which two or more layers having different refractive indexes are laminated may be reflective layer units having the same configuration or reflective layer units having different configurations. ..

The low refractive index layer constituting the reflective layer unit is mainly composed of the first metal oxide particles and the first binder resin, and the high refractive index layer is mainly composed of the second metal oxide particles and the first binder resin. It is composed of two binder resins.

(Binder resin that constitutes each refractive index layer)
In the present invention, the low refractive index layer contains the first binder resin and the high refractive index layer contains the second binder resin. As a method for forming each layer, a binder resin, preferably a water-soluble binder resin, for example, a polyvinyl alcohol resin as a material for forming each refractive index layer is used as a coating film forming material, and a wet coating method, for example, a gravure printing method , Flexographic printing, screen printing, roll coating, bar coating, dip coating, spin coating, casting, die coating, blade coating, bar coating, gravure coating, curtain coating, spray coating , A doctor coat method, an ink jet method or the like can be used for lamination.

These wet coating methods have a wide range of choices because the coating apparatus used is simple and the heat resistance of the base material does not matter. In particular, when a resin base material is used as the base material, it is an effective film forming method. For example, by applying the wet coating method, a continuous production mass production method such as a roll-to-roll method can be adopted, which is advantageous in terms of cost and process time. In addition, since each refractive index layer containing a binder resin has high flexibility, even when wound in a roll shape during production or transportation, these defects are less likely to occur and have an advantage of being easy to handle. is there.

<Binder resin for low refractive index layer>
A conventionally known binder resin can be used in the low refractive index layer according to the present invention.

In the low refractive index layer according to the present invention, it is particularly preferable to use a polyvinyl alcohol resin as a binder resin.

The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average polymerization degree of 1000 or more, and particularly preferably 1500 to 5000. Further, the saponification degree is preferably 70 to 100%, and particularly preferably 80 to 99.9%.

The polyvinyl alcohol used in the present invention may be a synthetic product or a commercially available product. Examples of commercial products used as polyvinyl alcohol include, for example, PVA-102, PVA-103, PVA-105, PVA-110, PVA-117, PVA-120, PVA-124, PVA-203, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-235 (above, Kuraray Co., Ltd.), JC-25, JC-33, JF-03, JF-04, JF-05, JP-. 03, JP-04, JP-05, JP-45 (above, Vinegar Japan Poval Co., Ltd. make) etc. are mentioned.

The binder resin according to the present invention may contain modified polyvinyl alcohol partially modified in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, as long as the effects of the present invention are not impaired. When such a modified polyvinyl alcohol is contained, the adhesion, water resistance and flexibility of the film may be improved.

Examples of the modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonion-modified polyvinyl alcohol, and vinyl alcohol-based polymer. Further, vinyl acetate resin (for example, "EXCEVAL" manufactured by Kuraray Co., Ltd.), polyvinyl acetal resin obtained by reacting polyvinyl alcohol with an aldehyde (for example, "Eslec" manufactured by Sekisui Chemical Co., Ltd.), silanol having a silanol group. Modified polyvinyl alcohol (for example, "R-1130" manufactured by Kuraray Co., Ltd.), modified polyvinyl alcohol-based resin having an acetoacetyl group in the molecule (for example, "Gosephimmer (registered trademark) Z/" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) WR series”) and the like are also included in the polyvinyl alcohol-based resin.

The anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A 1-206088, JP-A 61-237681 and 63-307979. A copolymer of such a vinyl alcohol and a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265 can be mentioned.

As the nonion-modified polyvinyl alcohol, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group to a part of vinyl alcohol as described in JP-A-7-9758, and JP-A-8-25795. Block copolymer of vinyl compound and vinyl alcohol having a hydrophobic group as described, silanol-modified polyvinyl alcohol having a silanol group, reactivity having a reactive group such as acetoacetyl group, carbonyl group and carboxy group Examples include group-modified polyvinyl alcohol.

Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups as described in JP-A-61-10483, which are main chains or side chains of the polyvinyl alcohol. The polyvinyl alcohol contained therein is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the vinyl alcohol-based polymer include EXCEVAL (trade name: manufactured by Kuraray Co., Ltd.) and Nichigo G polymer (trade name: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

In the low refractive index layer, in addition to the water-soluble polyester resin and the polyvinyl alcohol-based resin described above, other binder resins can be applied as long as the effects of the present invention are not impaired.

<Binder resin for high refractive index layer>
As the binder resin applicable to the high refractive index layer, from the viewpoint of good film formability, it is particularly preferable to apply the same polyvinyl alcohol-based resin as described for the low refractive index layer, but in addition, Polycarbonate, poly(meth)acrylate and the like can be used.

The binder resin forming the high refractive index layer may be one kind or two or more kinds.

The poly(meth)acrylate is a polymer of acrylic acid ester or methacrylic acid ester, and examples thereof include polymethyl methacrylate and polyethyl methacrylate.

The weight average molecular weight of polycarbonate and poly(meth)acrylate contained in the high refractive index layer is about 10,000 to 1,000,000, and preferably 50,000 to 800,000. As the weight average molecular weight, a value measured by gel permeation chromatography (GPC) is adopted.

<Other water-soluble binder resins>
Further, other water-soluble binder resins applicable to the low refractive index layer and the high refractive index layer according to the present invention include, for example, gelatin, celluloses, thickening polysaccharides, polymers having a reactive functional group, and the like. For example, JP 2012-27288 A, JP 2012-139938 A, JP 2012-185342 A, JP 2012-215733 A, and JP 2012-220708 A for details. JP, 2012-242644 A, JP 2012-252137 A, JP 2013-4916 A, JP 2013-97248 A, JP 2013-148849 A, JP 2014-89347 A, and Reference can be made to the descriptions in Japanese Unexamined Patent Publication No. 2014-201450, Japanese Unexamined Patent Publication No. 2014-215513, and the like.

(Metal oxide particles)
In the present invention, the low refractive index layer and the high refractive index layer preferably contain metal oxide particles.

<Metal Oxide Particles in Low Refractive Index Layer: First Metal Oxide Particles>
In the optical reflective film of the present invention, silicon oxide (silicon dioxide) is used as the metal oxide particles in the low refractive index layer. Specific examples include synthetic amorphous silica, colloidal silica, zinc oxide, alumina, colloidal alumina and the like. Of these, colloidal silica sol, particularly acidic colloidal silica sol, is more preferable, and colloidal silica dispersed in an organic solvent is particularly preferable. Further, in order to further reduce the refractive index, hollow fine particles having pores inside the particles may be used as the metal oxide particles of the low refractive index layer, and particularly hollow fine particles of silicon oxide (silicon dioxide) are preferable. .. Further, known metal oxide particles (inorganic oxide particles) other than silicon oxide can also be used. For adjusting the refractive index, the metal oxide particles contained in the low refractive index layer may be used alone or in combination of two or more.

The silicon oxide particles contained in the low refractive index layer preferably have an average particle diameter (number average; diameter) of 3 to 100 nm. The average particle diameter of the primary particles of silicon dioxide dispersed in the state of primary particles (particle diameter in a dispersion state before coating) is more preferably 3 to 50 nm, further preferably 1 to 40 nm. Particularly preferred is 3 to 20 nm, and most preferred is 4 to 10 nm. The average particle size of the secondary particles is preferably 30 nm or less from the viewpoint of less haze and excellent visible light transmittance.

Further, the particle diameter of the silicon oxide particles contained in the low refractive index layer can be determined by the volume average particle diameter in addition to the primary average particle diameter.

The colloidal silica used in the present invention is obtained by heating and aging a silica sol obtained by metathesis of sodium silicate by an acid or the like and passing through an ion exchange resin layer. For example, JP-A-57-14091. JP-A-60-219083, JP-A-60-219084, JP-A-61-27921, JP-A-61-188183, JP-A-63-17807, and JP-A-4- No. 93284, No. 5-278324, No. 6-92011, No. 6-183134, No. 6-297830, No. 7-81214, No. 7-101142. It is described in Japanese Patent Laid-Open No. 7-179029, Japanese Patent Laid-Open No. 7-137431, International Publication No. 94/26530, and the like.

As such colloidal silica, a synthetic product or a commercially available product may be used. Examples of commercially available products include Snowtex series (Snowtex OS, OXS, S, OS, 20, 30, 40, O, N, C, etc.) sold by Nissan Chemical Industries, Ltd.

The colloidal silica may have its surface cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.

Further, as the silicon oxide particles of the low refractive index layer, hollow particles can be used as described above. When hollow fine particles are used, the average particle pore size is preferably 3 to 70 nm, more preferably 5 to 50 nm, and further preferably 5 to 45 nm. The average particle pore size of the hollow fine particles is the average value of the inner diameters of the hollow fine particles. When the average particle pore diameter of the hollow fine particles is within the above range, the refractive index of the low refractive index layer is sufficiently lowered. The average particle pore size is an electron microscopic observation, in which 50 or more pore sizes that can be observed as a circle, an ellipse, or a substantially circular ellipse are randomly observed, the pore size of each particle is determined, and the number average value thereof is obtained. It can be obtained by The average particle pore diameter means the smallest distance among the distances between two parallel lines that surround the outer edge of the pore diameter that can be observed as a circle, an ellipse, or a substantially circle or an ellipse.

The content of silicon oxide particles in the low refractive index layer is preferably 20 to 90% by mass, more preferably 30 to 85% by mass, and 40 to 40% by mass based on the total solid content of the low refractive index layer. It is more preferably 80% by mass. When it is 20% by mass or more, a desired refractive index is obtained, and when it is 90% by mass or less, the coating property is good, which is preferable.

The silicon oxide particles of the low refractive index layer and the two or more kinds of cationic polymers may be contained in at least one low refractive index layer.

<Metal Oxide Particles in High Refractive Index Layer: Second Metal Oxide Particles>
The high refractive index layer according to the present invention preferably contains the second metal oxide particles. The second metal oxide particles applied to the high refractive index layer are preferably different from the first metal oxide particles applied to the low refractive index layer described above.

Examples of the metal oxide particles used in the high refractive index layer according to the present invention include titanium oxide particles, zirconium oxide particles, zinc oxide particles, alumina particles, colloidal alumina, niobium oxide particles, europium oxide particles, and zircon particles. You can The metal oxide particles may be used alone or in combination of two or more. Among the above metal oxide particles, it is preferable to contain zirconium oxide particles. The high refractive index layer containing zirconium oxide particles is transparent and can express a higher refractive index. Moreover, since the photocatalytic activity is low, the light resistance and weather resistance of the high refractive index layer and the adjacent low refractive index layer are high. In the present invention, zirconium oxide means zirconium dioxide (ZrO ₂ ).

The zirconium oxide particles may be cubic crystal, tetragonal crystal, or a mixture thereof.

The size of the zirconium oxide particles contained in the high refractive index layer is not particularly limited, but can be determined by the volume average particle diameter or primary average particle diameter. The volume average particle diameter of the zirconium oxide particles used in the high refractive index layer is preferably 100 nm or less, more preferably 1 to 100 nm, further preferably 2 to 50 nm. The primary average particle size of the zirconium oxide particles used in the high refractive index layer is preferably 100 nm or less, more preferably 1 to 100 nm, and even more preferably 2 to 50 nm. A volume average particle diameter or a primary average particle diameter of 1 nm or more and 100 nm or less is preferable from the viewpoint of less haze and excellent visible light transmittance.

The volume average particle size referred to in the present specification means a method of observing the particles themselves using a laser diffraction scattering method, a dynamic light scattering method, or an electron microscope, or particles appearing on the cross section or surface of the refractive index layer. By observing the image with an electron microscope, the particle diameters of 1000 arbitrary particles are measured, and the particles having the particle diameters of d1, d2...di...dk are n1, n2...ni, respectively. ... In a group of nk existing particles, when the volume per particle is vi, the volume average particle diameter is represented by mv={Σ(vi·di)}/{Σ(vi)} Calculate the volume weighted average particle size.

In addition, in the present specification, the primary average particle diameter can be measured from an electron micrograph by a transmission electron microscope (TEM) or the like. It may be measured by a particle size distribution meter using a dynamic light scattering method, a static light scattering method, or the like.

When obtained from a transmission electron microscope, the primary average particle size of the particles is obtained by observing the particles themselves or particles appearing on the cross section or surface of the refractive index layer with an electron microscope and measuring the particle size of 1000 arbitrary particles. , The simple average value (number average) is obtained. Here, the particle size of each particle is represented by the diameter assuming a circle equal to the projected area.

Further, as the zirconium oxide particles, particles obtained by modifying the surface of an aqueous zirconium oxide sol to be dispersed in an organic solvent or the like may be used.

As a method for preparing zirconium oxide particles or a dispersion thereof, any conventionally known method can be used. For example, as described in JP-A-2014-80361, a method of reacting a zirconium salt with an alkali in water to prepare a slurry of zirconium oxide particles, adding an organic acid, and performing hydrothermal treatment can be used. ..

As the zirconium oxide particles, commercially available particles may be used, and for example, SZR-W, SZR-CW, SZR-M, SZR-K and the like (above, manufactured by Sakai Chemical Industry Co., Ltd.) are preferably used. You can

Further, the zirconium oxide particles used in the present invention are preferably monodisperse.

The content of the zirconium oxide particles in the high refractive index layer is not particularly limited, but is preferably 15 to 95 mass% and more preferably 20 to 90 mass% with respect to the total solid content of the high refractive index layer. It is more preferably 30 to 90% by mass. Within the above range, good optical reflection characteristics can be obtained.

(Metal oxide particles used for high refractive index layer)
In the light reflecting film of the present invention, in the high refractive index layer, in addition to zirconium oxide particles, titanium oxide, tin oxide, zinc oxide, alumina, colloidal alumina, niobium oxide, metal oxide particles such as europium oxide (high refractive index Rate metal oxide fine particles) can be used. The high-refractive-index metal oxide fine particles may be used alone or in combination of two or more in order to adjust the refractive index. The size of the high refractive index metal oxide fine particles other than zirconium oxide is not particularly limited, but the volume average particle diameter is preferably 1 to 100 nm or less, and more preferably 3 to 50 nm. The primary average particle diameter is preferably 1 to 100 nm or less, more preferably 3 to 50 nm. The content of the high-refractive-index metal oxide fine particles in the high-refractive-index layer is not particularly limited, but when combined with zirconium oxide, the content of the zirconium oxide particles and the high-refractive-index metal oxide fine particles are contained. It is preferable that the sum of the amount and the total solid content of the high refractive index layer is adjusted to 15 to 95% by mass, more preferably 20 to 80% by mass, and 30 to 80% by mass. It is even more preferable to have.

When combining zirconium oxide and other metal oxide fine particles, the total amount of metal oxide particles used in the high refractive index layer (the total amount of zirconium oxide particles and the high refractive index metal oxide fine particles other than zirconium oxide) On the other hand, the content of the zirconium oxide particles is preferably 80 to 100% by mass, preferably 90 to 100% by mass, and more preferably 100% by mass.

The zirconium oxide particles of the high refractive index layer may be contained in at least one of the plural high refractive index layers.

(Other additives applicable to each refractive index layer)
Various additives applicable to the high refractive index layer and the low refractive index layer according to the present invention are listed below. For example, the ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, and JP-A-57-87989. Anti-fading agents, anions and cations described in JP-A No. 60-72785, JP-A No. 61-146591, JP-A No. 1-95091 and JP-A No. 3-13376. Alternatively, various nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-219266. Whitening agents, pH adjusting agents such as sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc., defoaming agents, lubricants such as diethylene glycol, antiseptic, etc. Agents, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, polyester resins, viscosity reducing agents, lubricants, infrared absorbing agents, dyes, pigments Various known additives such as

[Ratio of the number of layers of a plurality of reflective layer units]
In the light reflecting film of the present invention, in a structure having two or more reflecting layer units, the number of layers of one reflecting layer unit facing each other with the adhesive layer sandwiched between is L1, and the number of layers of the other reflecting layer unit is L2. At this time, it is preferable that the ratio value L1/L2 of the number of layers of each reflective layer unit is within the range of 0.5 to 1.5.

As shown in FIG. 1, in the case of a reflective layer unit in which two layers having different refractive indexes are laminated, a layer of the first reflective layer unit (3A) arranged via an adhesive layer (AL). When the number is L1 and the number of layers of the second reflective layer unit (3B) is L2, L1/L2 is preferably in the range of 0.5 to 1.5.

Also, as shown in FIG. 2, when the reflective layer unit in which two or more layers having different refractive indexes are laminated is composed of three units, the number of layers of the first reflective layer unit (3A) is L1, and the second reflective layer unit When the number of layers of the layer unit (3B) is L2 and the number of layers of the third reflective layer unit (3C) is L3, it is preferable to satisfy the conditions defined by the following formulas (1) and (2).

Formula (1)
L1/L2=0.5 to 1.5
Formula (2)
L2/L3=0.5 to 1.5
[Adhesive layer]
One of the features of the light reflecting film of the present invention is that it has an adhesive layer between two or more reflecting layer units.

The adhesive layer according to the present invention is usually provided on the surface of the reflective layer unit opposite to the base film, at a position facing the other reflective layer unit.

As the adhesive constituting the adhesive layer applicable to the present invention, a polyester-based adhesive, a urethane-based adhesive, a polyvinyl acetate-based adhesive, an acrylic-based adhesive, a nitrile rubber or the like is used, and the photo-curable or An adhesive containing a thermosetting resin as a main component can be used.

The acrylic adhesive used may be either a solvent-based adhesive or an emulsion-based adhesive, but a solvent-based adhesive is preferable because it is easy to enhance the adhesive strength and the like, and among them, those obtained by solution polymerization are preferable. As a raw material in the case of producing such a solvent-based acrylic adhesive by solution polymerization, for example, as a main monomer serving as a skeleton, an acrylic ester such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, or ocryyl acrylate, As a comonomer to improve cohesive strength, vinyl acetate, acrylonitrile, styrene, methyl methacrylate, etc., to further promote cross-linking, to give stable adhesive strength, and to maintain some adhesive strength even in the presence of water Examples of the functional group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, glycidyl methacrylate and the like. As the main polymer for the adhesive layer, a polymer having a low glass transition temperature (Tg) such as butyl acrylate is particularly useful because it requires particularly high tack.

Examples of commercially available acrylic adhesives include COPONYL series (manufactured by Nippon Synthetic Chemical Co., Ltd.).

Further, for forming the curable adhesive layer, for example, a radical curable adhesive is preferably used as the adhesive composition. Examples of the radical curable adhesive include active energy ray curable adhesives such as electron beam curable adhesives and ultraviolet curable adhesives. In particular, an active energy ray curable type that can be cured in a short time is preferable, and a UV curable adhesive that can be cured with low energy is more preferable.

Ultraviolet curable adhesives can be roughly classified into radical polymerization curable adhesives and cationic polymerization curable adhesives. In addition, the radical polymerization curable adhesive can be used as a thermosetting adhesive.

As the ultraviolet ray used for the curing, a gallium-encapsulated metal halide lamp or an LED light source emitting light in the wavelength range of 380 to 440 nm is preferable. For example, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, incandescent lamp, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excimer laser or sunlight as a light source, It is also possible to use by blocking light having a wavelength shorter than 380 nm using a bandpass filter.

Examples of the curable component of the radical polymerization curable adhesive include a compound having a (meth)acryloyl group and a compound having a vinyl group. These curable components may be monofunctional or bifunctional or higher. Moreover, these curable components can be used individually by 1 type or in combination of 2 or more types. As these curable components, for example, compounds having a (meth)acryloyl group are suitable.

Examples of the curable component of the cationic polymerization curable adhesive include compounds having an epoxy group or an oxetanyl group. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used. The preferred epoxy compound is a compound having at least two epoxy groups and at least one aromatic ring in the molecule, or at least two epoxy groups in the molecule, at least one of which has an alicyclic ring. Examples thereof include compounds that are formed between two adjacent carbon atoms that form the structure.

As the water-based adhesive, an adhesive containing a vinyl polymer or the like is preferably used, and as the vinyl polymer, a polyvinyl alcohol-based resin is preferable. As the polyvinyl alcohol-based resin, an adhesive containing a polyvinyl alcohol-based resin having an acetoacetyl group is more preferable from the viewpoint of improving durability. As the cross-linking agent that can be added to the polyvinyl alcohol resin, a compound having at least two functional groups reactive with the polyvinyl alcohol resin can be preferably used. For example, boric acid, borax, carboxylic acid compounds, alkyldiamines; isocyanates; epoxies; monoaldehydes; dialdehydes; amino-formaldehyde resins; further salts of divalent or trivalent metals and oxides thereof. Are listed.

The adhesive forming the curable adhesive layer may appropriately contain additives if necessary. Examples of additives include silane coupling agents, coupling agents such as titanium coupling agents, adhesion promoters represented by ethylene oxide, additives that improve wettability with transparent films, acryloxy group compounds and hydrocarbon-based compounds. (Natural and synthetic resins) and the like, additives for improving mechanical strength and processability, ultraviolet absorbers, antioxidants, dyes, processing aids, ion trap agents, antioxidants, tackifiers, Examples include fillers (metal oxide particles), plasticizers, leveling agents, foaming inhibitors, antistatic cracks, heat stabilizers, hydrolysis stabilizers, and other stabilizers.

Among the above additives, in the adhesive layer according to the present invention, as described above, the content of the inorganic fine particles is preferably 20% by volume or less with respect to the total volume of the adhesive layer, and particularly, It is preferable that no inorganic fine particles are contained.

Examples of the inorganic fine particles applicable to the adhesive layer include zinc oxide, synthetic amorphous silica, silicon dioxide such as colloidal silica, alumina, and colloidal alumina.

[Method for producing light reflecting film]
In the method for producing a light-reflecting film of the present invention, finally, a pair of base film as illustrated in FIGS. 1 to 3 and two reflecting layer units in which two or more layers having different refractive indexes are laminated are provided. A reflective layer unit group having the adhesive layer between the two or more reflective layer units and including the two or more reflective layer units and the adhesive layer is sandwiched between the pair of base material films. The two laminated bodies having at least one reflection layer unit on the base film are arranged so that the reflection layer unit surface sides face each other, and are manufactured by bonding via an adhesive layer. And

Specifically, the method shown in FIG. 5 is preferably a method in which two film units are bonded together via an adhesive layer to produce a light reflecting film.

(The manufacturing method of the light reflection film of the structure shown in FIG. 1)
Hereinafter, as an example, a method for manufacturing the light reflecting film having the configuration illustrated in FIG. 1 will be described.

FIG. 5 is a process schematic view showing an example of the method for producing a light reflecting film of the present invention.

In FIG. 5, as the first film unit (F1), a first reflective layer unit (3A) in which two or more layers having different refractive indexes are laminated on the base film 1 (2A) is formed.

On the other hand, as the second film unit (F2), a second reflective layer unit (3B) in which two or more layers having different refractive indexes are laminated on the base film 2 (2B) is formed.

While continuously transporting the second film unit (F2), the coating liquid for forming an adhesive layer is applied from the coater (6) to the second reflective layer unit (3B) to form the adhesive layer (AL). .. As the applicable coater (6), for example, a gravure coater, a dip coater, an extrusion coater, a reverse coater, a wire bar coater, a die coater, an inkjet method, or the like can be appropriately selected and applied.

Then, the second film unit (F2) on which the adhesive layer (AL) is formed and the first film unit (F1) are continuously conveyed so that the reflection layer units face each other, and the first film unit (F1) is conveyed. The first reflection layer unit (3A) of (F1) and the adhesive layer (AL) of the second film unit (F2) are associated with each other at the association point (P), and the rubber pressure roller (7) is provided. The light-reflecting film of the present invention having two reflecting layer units is produced by passing through a roller gap (nip portion) formed by the metal heating roller (8) and bonding the two.

Further, when an ultraviolet curable resin material is used as the adhesive layer forming material, an ultraviolet irradiation light source (9) for irradiating ultraviolet rays for curing is provided further downstream.

(The manufacturing method of the light reflection film of the structure which has the three reflection layer units shown in FIG. 2)
As a method for producing a light reflecting film having three reflecting layer units as shown in FIG. 2, a third reflecting layer unit and a second reflecting layer unit are bonded to each other on a base film via an adhesive layer. After adhering and further forming an adhesive layer, it can be manufactured by laminating with the first reflective layer unit. In the present invention, as described with reference to FIG. Particularly preferred is a method of producing a light reflecting film having three reflecting layer units as shown in FIG. 2 using the body.

(Method of forming reflective layer unit)
Next, a method of forming the plurality of reflective layer units will be described.

As described above, the method for forming the reflective layer unit may be a method in which at least one unit composed of a high refractive index layer and a low refractive index layer can be laminated on the base film. Thus, any method can be used.

Specifically, it is preferable that a high refractive index layer and a low refractive index layer are alternately coated and dried on a substrate film to form a laminate. Specifically, the following modes are mentioned.

(1) A high refractive index layer coating liquid is applied and dried on a base film to form a high refractive index layer, and then a low refractive index layer coating liquid is applied and dried to form a low refractive index layer, A method for forming a reflective layer unit by repeating this in sequence,
(2) A low refractive index layer coating liquid is applied and dried on the base film to form a low refractive index layer, and then a high refractive index layer coating liquid is applied and dried to form a high refractive index layer, A method for forming a reflective layer unit by repeating this in sequence,
(3) A high-refractive-index layer coating solution and a low-refractive-index layer coating solution are sequentially layered on a substrate film and then dried to form a predetermined number of high-refractive-index layers and low-refractive-index layers. A method of forming a reflective layer unit,
(4) A high-refractive-index layer coating solution and a low-refractive-index layer coating solution are laminated in a wet state on a substrate film, and a predetermined number of layers are simultaneously multilayer-coated and dried to form a high-refractive-index layer. And a method for forming a reflective layer unit including a low refractive index layer,
And so on.

Of these, the method (4) is preferable because it provides a simpler manufacturing process. That is, the method for forming the reflective layer unit in the method for producing a light reflective film of the present invention preferably includes laminating a plurality of high refractive index layers and low refractive index layers by an aqueous simultaneous multilayer coating method.

As a coating method, for example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or a hopper described in US Pat. Nos. 2,761,419 and 2,761,791 is used. A slide bead coating method, an extrusion coating method and the like are preferably used.

The solvent for preparing the high refractive index layer coating liquid and the low refractive index layer coating liquid is not particularly limited, but water, an organic solvent, or a mixed solvent thereof is preferable. In the present invention, it is preferable to mainly use polyvinyl alcohol as the binder resin constituting each refractive index layer, but by using polyvinyl alcohol in this way, coating with an aqueous solvent becomes possible. Furthermore, in the present invention, it is preferable to add two or more kinds of cationic polymers to the low refractive index layer coating liquid in order to reduce haze and suppress cracks. Compared with the case where an organic solvent is used, the aqueous solvent does not require a large-scale production facility, and is therefore preferable in terms of productivity and is also preferable in terms of environmental protection.

Examples of the organic solvent include alcohols such as methanol and ethanol, ethyl acetate, butyl acetate, esters such as propylene glycol monomethyl ether acetate, ethers such as diethyl ether and propylene glycol monomethyl ether, and amides such as dimethylformamide. , Acetone, methyl ethyl ketone, and other ketones. These organic solvents may be used alone or in combination of two or more. From the standpoint of environment and ease of operation, the solvent of the coating liquid is preferably an aqueous solvent, more preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate, and particularly preferably water.

When a mixed solvent of water and a small amount of an organic solvent is used, the content of water in the mixed solvent is preferably 80 to 99.9% by mass, based on 100% by mass of the entire mixed solvent, and 85 to 99. It is more preferably 0.5% by mass. Here, when the content is 80% by mass or more, the volume fluctuation due to the volatilization of the solvent can be reduced and the handling is improved, and when it is 99.9% by mass or less, the homogeneity at the time of adding the liquid is increased and the stability is improved. This is because the obtained liquid physical properties can be obtained.

The concentration of the resin in the coating liquid for the high refractive index layer (when using a plurality of types of resins, the total concentration thereof) is preferably 0.5 to 10% by mass. Further, the total concentration of the metal oxide particles containing zirconium oxide in the coating liquid for high refractive index layer is preferably 1 to 50% by mass.

The concentration of the resin in the low refractive index layer coating liquid is preferably 0.5 to 10% by mass. The total concentration of metal oxide particles including silicon oxide particles in the low refractive index layer coating liquid is preferably 1 to 50% by mass. Further, the content of two or more kinds of cationic polymers in the low refractive index layer coating liquid is such that each cationic polymer is, for example, 0.5 to 20% by mass with respect to the total mass of the metal oxide particles containing silicon oxide particles. It is 2 to 20 mass %, more preferably 3 to 10 mass %, further preferably 1 to 10 mass %, and even more preferably 2 to 5 mass %. ..

The method for preparing the high refractive index layer coating liquid is not particularly limited, and for example, metal oxide particles, a resin binder, for example, polyvinyl alcohol, and other additives that are added as necessary are added and mixed with stirring. There is a method. At this time, the order of addition of each component is not particularly limited, and each component may be sequentially added and mixed while stirring, or may be added and mixed at once while stirring.

The method for preparing the low refractive index layer coating liquid is not particularly limited, and for example, metal oxide particles, a resin binder, for example, polyvinyl alcohol, and other additives that are added as necessary are added and mixed with stirring. There is a method. At this time, the order of addition of each component is not particularly limited, and each component may be sequentially added and mixed while stirring, or may be added and mixed at once while stirring.

In the present invention, when simultaneous multi-layer coating is performed, it is preferable that the saponification degrees of the polyvinyl alcohols used in the high refractive index layer coating liquid and the low refractive index layer coating liquid are different. Due to the different degree of saponification, mixing of layers can be suppressed in each step of coating and drying.

When the slide hopper coating method is used, the temperature of the high refractive index layer coating liquid and the low refractive index layer coating liquid when performing simultaneous multilayer coating is preferably 25 to 60°C, and 30 to 45°C. Is more preferable. When using the curtain coating method, the temperature range of 25 to 60°C is preferable, and the temperature range of 30 to 45°C is more preferable.

The viscosities of the high refractive index layer coating liquid and the low refractive index layer coating liquid when performing simultaneous multilayer coating are not particularly limited. However, when the slide bead coating method is used, the temperature range of the coating solution is preferably 5 to 160 mPa·s, more preferably 60 to 140 mPa·s. When the curtain coating method is used, the temperature range of the coating liquid is preferably 5 to 1200 mPa·s, more preferably 25 to 500 mPa·s. Within such a viscosity range, simultaneous multilayer coating can be efficiently performed.

The conditions of the coating and drying methods are not particularly limited. For example, in the case of the sequential coating method, first, either the high refractive index layer coating solution or the low refractive index layer coating solution heated to 30 to 60° C. is first applied. After coating and drying on the base film to form a layer, the other coating solution is coated on this layer and dried to form a laminated film precursor (unit). Next, the number of units required to develop the desired shielding performance is sequentially applied by the above method, dried and laminated to obtain a laminated film precursor. When drying, the formed coating film is preferably dried at 30° C. or higher. For example, it is preferable to dry at a wet bulb temperature of 5 to 50°C and a film surface temperature of 5 to 100°C (preferably 10 to 50°C). For example, hot air of 40 to 60°C is blown for 1 to 5 seconds. dry.

In addition, the conditions of the coating and drying method when performing simultaneous multilayer coating are as follows: The high refractive index layer coating liquid and the low refractive index layer coating liquid are heated to 30 to 60° C. to coat the high refractive index layer on the substrate. After the simultaneous multilayer coating of the liquid and the low refractive index layer coating liquid is performed, the temperature of the formed coating film is preferably once cooled (set) to preferably 1 to 15° C. and then dried at 10° C. or higher. More preferable drying conditions are conditions of a wet bulb temperature of 5 to 50° C. and a film surface temperature of 10 to 50° C. For example, hot air of 40 to 80° C. is blown for 1 to 5 seconds to dry. The cooling method immediately after coating is preferably a horizontal setting method from the viewpoint of improving the uniformity of the formed coating film.

[Design of layer structure]
The light reflecting film of the present invention includes at least two reflecting layer units in which a high refractive index layer and a low refractive index layer are laminated. Preferably, it has a multilayer optical interference film formed by alternately laminating a high refractive index layer and a low refractive index layer on one surface or both surfaces of a substrate. From the viewpoint of productivity, the range of the total number of high refractive index layers and low refractive index layers per one surface of the substrate is preferably 100 layers or less, more preferably 45 layers or less. The lower limit of the total number of high refractive index layers and low refractive index layers per one side of the substrate is not particularly limited, but is preferably 5 or more.

Generally, in the reflective layer unit, it is preferable to design a large difference in refractive index between the high refractive index layer and the low refractive index layer from the viewpoint that the reflectance for a desired light beam can be increased with a small number of layers. .. In the present invention, the difference in refractive index between at least two adjacent layers (high refractive index layer and low refractive index layer) is preferably 0.15 or more, more preferably 0.2 or more, and particularly preferably 0. .21 or more. The upper limit is not particularly limited, but is usually 0.5 or less.

The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain a near infrared reflectance of 90% or more, if the difference in refractive index is smaller than 0.1, it is necessary to stack 200 layers or more, which not only lowers the productivity but also causes scattering at the stacking interface. It may become large, the transparency may deteriorate, and it may be very difficult to manufacture without failure.

When the high refractive index layer and the low refractive index layer are alternately laminated in the reflective layer unit, the refractive index difference between the high refractive index layer and the low refractive index layer is within the range of the above preferable refractive index difference. It is preferable. However, for example, when the outermost layer is formed as a layer for protecting the film, or when the lowermost layer is formed as an adhesion improving layer with the substrate, etc., with respect to the outermost layer and the lowermost layer, the above-mentioned suitable refraction The configuration may be outside the range of the rate difference.

The light reflection film of the present invention can be made into a visible light reflection film or a near-infrared reflection film by changing the specific wavelength region for increasing the reflectance. That is, if the specific wavelength region for increasing the reflectance is set to the visible light region, it becomes a visible light reflection film, and if it is set to the near infrared region, it becomes a near infrared reflection film. Further, if the specific wavelength region for increasing the reflectance is set in the ultraviolet light region, the ultraviolet reflection film is obtained. When the light reflection film of the present invention is used as a heat shield film, it may be a (near) infrared reflection (shield) film. In the case of an infrared reflection film, a multilayer film is formed by laminating films having different refractive indexes on a polymer film, and the transmittance at 550 nm in the visible light region shown in JIS R3106 (1998) is 50% or more. It is preferably 70% or more, more preferably 75% or more. Further, the transmittance at 1200 nm is preferably 35% or less, more preferably 25% or less, and further preferably 20% or less. It is preferable to design the optical film thickness and the unit so as to be in such a suitable range. Further, it is preferable to have a region having a reflectance of more than 50% in the wavelength region of 900 to 1400 nm.

The infrared region of the incident spectrum of sunlight is related to the rise in the room temperature, and by blocking this, the rise in the room temperature can be suppressed. Looking at the cumulative energy ratio from the shortest infrared wavelength (760 nm) to the longest wavelength 3200 nm based on the weighting coefficient described in Japanese Industrial Standard JIS R3106 (1998), the infrared from the wavelength 760 nm to the longest wavelength 3200 nm When the cumulative energy from 760 nm to each wavelength is calculated with the total energy of the entire region being 100, the total energy from 760 to 1300 nm occupies about 75% of the entire infrared region. Therefore, it is efficient to shield the wavelength region up to 1300 nm for the energy saving effect by the heat ray shielding.

When the reflectance in the near-infrared light region (760 to 1300 nm) has a maximum peak value of about 80% or more, a reduction in sensible temperature can be obtained by sensory evaluation. For example, when the sensible temperature near the window facing the southeast method in the morning of August shielded the reflectance in the near infrared region to about 80% at the maximum peak value, there was a clear difference.

The multilayer film structure required for exhibiting such a function was obtained by optical simulation (FTG Software Associates Film DESIGN Version 2.23.3700) and was found to have a high refractive index of 1.7 or more, preferably 1.73 or more. It has been found that excellent characteristics can be obtained when 22 layers or more are laminated by using a rate layer. For example, looking at the simulation result of a model in which 22 layers of high-refractive index layers and low-refractive index layers (refractive index=1.45) are alternately laminated, the refractive index of the high refractive index layer is 1.6 and the reflectance is 30. %, but a reflectance of about 60% is obtained at 1.7.

The low refractive index layer preferably has a refractive index of 1.10 to 1.60, more preferably 1.30 to 1.50. The high refractive index layer preferably has a refractive index of 1.65 to 1.80, more preferably 1.70 to 1.75.

The thickness (layer thickness after drying) per one layer (excluding the lowermost layer and the outermost layer) of the refractive index layer is preferably 20 to 1000 nm, more preferably 50 to 500 nm, and more preferably 50 to 350 nm. Is more preferable.

The total thickness (including the substrate) of the light reflecting film of the present invention is preferably 12 to 315 μm, more preferably 15 to 200 μm, and further preferably 20 to 100 μm.

Furthermore, in order to improve the optical characteristics, the haze of the light reflecting film is preferably small, and more preferably 0 to 1.5%. From the viewpoint of durability, it is preferable that cracks after exposure be suppressed. In addition, haze shall refer to the value measured by the method of an Example.

[Total other structure of light reflection film]
The light reflection film has a configuration in which at least two reflection layer units each having a high refractive index layer and a low refractive index layer laminated on a base material, and an adhesive layer formed therebetween.

The light-reflecting film is a conductive layer, an antistatic layer, a gas barrier layer, an easy-adhesion layer (adhesive layer) under the base film or on the outermost surface layer on the side opposite to the base film for the purpose of adding further functions. Layer), antifouling layer, deodorant layer, drip layer, easy slip layer, hard coat layer, abrasion resistant layer, antireflection layer, electromagnetic wave shielding layer, ultraviolet absorbing layer, infrared absorbing layer, printing layer, fluorescent emitting layer. , Hologram layer, peeling layer, adhesive layer, infrared cut layer (metal layer, liquid crystal layer) other than the high refractive index layer and low refractive index layer, coloring layer (visible light absorbing layer), interlayer film used for laminated glass May have one or more functional layers such as.

The order of laminating the various functional layers described above in the light reflecting film is not particularly limited.

(Adhesive layer)
In the light-reflecting film of the present invention, an adhesive layer may be formed on the outermost surface of one of the pair of substrate films when it is attached to a window or the like. The constitution of the adhesive layer is not particularly limited and, for example, any of dry laminating agent, wet laminating agent, adhesive agent, heat sealing agent, hot melt agent and the like can be used.

As the adhesive, for example, polyester adhesive, urethane adhesive, polyvinyl acetate adhesive, acrylic adhesive, silicone adhesive, nitrile rubber, etc. are used.

The light-reflecting film of the present invention, when pasted to a window glass, spraying water on the window, a method of pasting the adhesive layer of the light-reflecting film to the glass surface in a wet state, a so-called water pasting method is reattached, repositioned, etc. It is preferably used from the viewpoint of. Therefore, an acrylic pressure-sensitive adhesive, which has a weak adhesive force in the presence of water under a wet condition, is preferably used.

Further, the thickness of the adhesive layer is preferably in the range of usually about 1 to 100 μm from the viewpoint of the adhesive effect, the drying speed, and the like.

The adhesive strength is preferably 2 to 30 N/25 mm, more preferably 4 to 20 N/25 mm, as the peel strength measured by the 180° peel test described in JIS K6854.

[Hard coat layer]
The light-reflecting film of the present invention may be laminated with a hard coat layer containing a resin curable by heat, ultraviolet rays or the like as a surface protective layer for enhancing scratch resistance. For example, a hard coat layer can be coated on the outermost surfaces of the two base material films.

Examples of the curable resin used in the hard coat layer include a thermosetting resin and an ultraviolet curable resin, but an ultraviolet curable resin is preferable because it is easy to mold, and among them, a pencil hardness of at least 2H is preferable. More preferable. Such curable resins can be used alone or in combination of two or more.

Examples of the ultraviolet curable resin include (meth)acrylate, urethane acrylate, polyester acrylate, epoxy acrylate, epoxy resin, and oxetane resin, and these can also be used as a solventless resin composition.

When the above ultraviolet curable resin is used, it is preferable to add a photopolymerization initiator to accelerate curing.

As the photopolymerization initiator, acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, fluoroamine compounds Are used. Specific examples of the photopolymerization initiator include 2,2'-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxycyclohexylphenyl ketone, 1-hydroxydimethylphenyl ketone, 2-methyl-4'-methylthio-2-mol. Acetophenones such as holinopropiophenone and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone 1, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl dimethyl retinal. Benzoin, benzophenone, 2,4'-dichlorobenzophenone, 4,4'-dichlorobenzophenone, benzophenones such as p-chlorobenzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, anthraquinones, thioxanthones, etc. .. These photopolymerization initiators may be used alone, or may be a combination of two or more kinds or a eutectic mixture. In particular, it is preferable to use acetophenones because of the stability of the curable composition and the polymerization reactivity.

As such a photopolymerization initiator, a commercially available product may be used, and preferred examples include Irgacure (registered trademark) 819, 184, 907, 651 manufactured by BASF Japan Ltd.

In this hard coat layer, as additives, for example, stabilizers, surfactants, infrared absorbers, ultraviolet absorbers, flame retardants, antistatic agents, antioxidants, heat stabilizers, lubricants, fillers, colorants, A dye, an adhesion control agent, etc. can also be contained.

The thickness of the hard coat layer is preferably 0.1 to 50 μm, and more preferably 1 to 20 μm from the viewpoints of improving the hard coat property and improving the transparency of the light reflection film.

The method for forming the hard coat layer is not particularly limited, and for example, after preparing a hard coat layer coating liquid containing the above components, the coating liquid is coated with a wire bar or the like, and the coating liquid is cured by heat or ultraviolet rays, Examples thereof include a method of forming a coat layer.

[Other layers]
The light reflection film of the present invention may have layers (other layers) other than the above-mentioned layers. For example, an intermediate layer can be provided as the other layer. Here, the "intermediate layer" means a layer between the base material and the optical reflection layer, or a layer between the base material and the hard coat layer. Examples of the constituent material of the intermediate layer include a polyester resin, a polyvinyl alcohol resin, a polyvinyl acetate resin, a polyvinyl acetal resin, an acrylic resin, and a urethane resin. A material having a low additive compatibility and a low Tg is preferable. Either may be used as long as it satisfies the conditions. The glass transition temperature (Tg) of the intermediate layer is preferably 30 to 120° C., because sufficient weather resistance can be obtained, and more preferably 30 to 90° C.

In the intermediate layer, as an additive, for example, a stabilizer, a surfactant, an infrared absorber, an ultraviolet absorber, a flame retardant, an antistatic agent, an antioxidant, a heat stabilizer, a lubricant, a filler, a colorant, a dye, An adhesion modifier or the like can be included.

[Application of light reflection film: optical reflector]
The light reflecting film of the present invention can be applied to a wide range of fields. For example, there is provided an optical reflector in which the light reflecting film is provided on at least one surface of a substrate. For example, a window sticking film such as a heat ray reflecting film that is attached to a facility (base) that is exposed to sunlight for a long period of time such as an outdoor window of a building or an automobile window, a film for agricultural greenhouses. Etc. are mainly used for the purpose of enhancing weather resistance. In particular, there may be mentioned a configuration in which the light reflection film according to the present invention is directly or via an adhesive agent attached to a substrate such as glass or glass substitute resin.

Specific examples of the substrate include glass, polycarbonate resin, polysulfone resin, acrylic resin, polyolefin resin, polyether resin, polyester resin, polyamide resin, polysulfide resin, unsaturated polyester resin, epoxy resin, melamine resin, phenol resin, Examples thereof include diallyl phthalate resin, polyimide resin, urethane resin, polyvinyl acetate resin, polyvinyl alcohol resin, styrene resin, vinyl chloride resin, metal plate and ceramics. The type of resin may be any of a thermoplastic resin, a thermosetting resin, and an ionizing radiation curable resin, and two or more kinds of these may be used in combination. The substrate can be manufactured by a known method such as extrusion molding, calender molding, injection molding, hollow molding, compression molding and the like. The thickness of the substrate is not particularly limited, but is usually 0.1 mm to 5 cm.

The adhesive layer or the pressure-sensitive adhesive layer for bonding the light reflecting film and the substrate is preferably installed so that the light reflecting film is on the side of the sunlight (heat ray) incident surface when it is bonded to a window glass or the like. If the light reflecting film is sandwiched between the window glass and the base material, it can be sealed from ambient gas such as moisture, which is preferable for durability. Even if the light reflecting film of the present invention is installed outdoors or on the outside of a car (for external sticking), it is preferable because it has environmental durability.

As the pressure-sensitive adhesive applicable to the present invention, the above-mentioned pressure-sensitive adhesive, for example, polyester-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, polyvinyl acetate-based pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, nitrile rubber, etc. are used. To be

It is preferable that the adhesive has durability against ultraviolet rays, and an acrylic adhesive or a silicone adhesive is preferable. Further, acrylic adhesives are preferable from the viewpoint of adhesive properties and cost. In particular, in the acrylic pressure-sensitive adhesive, the solvent type is preferred among the solvent type and the emulsion type because the peel strength is easily controlled. When a solution-polymerized polymer is used as the acrylic solvent-based pressure-sensitive adhesive, known monomers can be used as the monomer.

[Laminated glass]
Laminated glass is a member in which the light reflection film according to the present invention is bonded to a glass substrate via an intermediate film. Laminated glass can be used for building applications, residential applications, automotive applications, and the like.

One embodiment of the laminated glass has a structure in which a light reflection film is sandwiched between two plate glasses using two interlayer films. The light reflection film is the light reflection film of the present invention described above. The light reflecting film may have a structure in which a reflecting layer is laminated on one surface of a substrate and a hard coat layer is coated on the other surface. Further, the light reflecting film is obtained by bonding the other surface of the base material having the reflection layer laminated on one surface and the other surface of the base material having the hard coat layer laminated on the one surface with an adhesive layer. The configuration may be different.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” or “%” is used, but unless otherwise specified, “parts by mass” or “% by mass” is shown. Unless otherwise specified, each operation was performed at room temperature (25°C).

<<Production of light reflection film>>
[Production of Light Reflecting Film 1]
A light-reflecting film 1 having the structure shown in FIG. 1 was produced according to the method described below.

(Preparation of first film unit 1 (F1))
<Preparation of coating liquid 1 for forming a low refractive index layer>
A coating liquid 1 for forming a low refractive index layer was prepared according to the following method.

Methyldiallylamine hydrochloride polymer (including tertiary amine salt) (PAS M-1, weight average molecular weight 20000, 50 mass% aqueous solution, manufactured by Nitto Bo Medical Co., Ltd.) 4.0 g as a cationic polymer in a stirring container, and diallyldimethylammonium. Chloride polymer (including quaternary ammonium group) (PAS H-5, weight average molecular weight 30,000, 28 mass% aqueous solution, manufactured by Nitto Bo Medical Co., Ltd.) 5.0 g, rinse water 31 g, and boric acid (3 mass% aqueous solution) ) 31.9 g were mixed. To this, 489.9 g of an aqueous solution of 10 mass% acidic colloidal silica (ST-OXS, concentration 10%, average primary particle size: 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) was added. This was heated to 40° C. with stirring. Here, 86.3% by weight aqueous solution of polyvinyl alcohol (JP-45, degree of polymerization 4500, degree of saponification 88 mol%, manufactured by Nippon Vinegar Bipovar Co., Ltd.) 386.3 g, emulsion resin (Superflex 650, Daiichi Kogyo Seiyaku Co., Ltd.) A mixture of 30.5 g and 5% by mass of a surfactant solution (6.3 g of softazoline LMEB-R, Kawaken Fine Chemicals Co., Ltd.) and 15 g of pure water was added, and the mixture was stirred and mixed at 40° C. to obtain a low refractive index. A coating liquid 1 for forming a rate layer was obtained. The refractive index of the single layer produced by using the coating liquid 1 for forming a low refractive index layer was 1.48. The method for measuring the refractive index is as follows (the same applies hereinafter).

<Measurement of single film refractive index of each layer>
In order to measure the refractive index, a sample was prepared by coating the above-mentioned high refractive index layer coating liquid 1 in a single layer on a substrate, and after cutting this sample into 10 cm×10 cm, the refractive index was determined according to the following method. .. A spectrophotometer U-4100 (solid sample measurement system) manufactured by Hitachi was used to roughen the surface (back surface) opposite to the measurement surface of each sample, and then perform light absorption processing with a black spray. The reflectance of 400 to 2500 nm was measured under the condition of 5° specular reflection while preventing the reflection of light on the back surface, and the refractive index was obtained from the result. The following refractive index was set to 1000 nm in consideration of the wavelength dependence of the refractive index.

<Preparation of coating liquid 1 for forming a high refractive index layer>
An aqueous citric acid solution (1.9% by mass) was added to 384.8 g of a 30% by mass dispersion of zirconium oxide particles (SZR-W, zirconia sol, particle size distribution: D50 3-5 nm, manufactured by Sakai Chemical Industry Co., Ltd.). 175.4 g was added. 1.94 g of a 5 mass% aqueous solution of a surfactant (Softofazoline LMEB-R, manufactured by Kawaken Fine Chemicals Co., Ltd.) was added to this, and this was heated to 40°C. Next, 120.4 g of an 8 mass% aqueous solution of ethylene-modified polyvinyl alcohol (Kuraray Co., Ltd., EXCEVAL RS2117, saponification degree: 97.5 to 99 mol %) was added, and further 9.9 g of pure water was added. After stirring this for 10 minutes, 240.8 g of a 6% by mass aqueous solution of polyvinyl alcohol (JC-40, saponification degree: 99 mol% or more, manufactured by Nippon Vine & Poval Co., Ltd.) and 66.7 g of pure water were added. Then, it stirred at 40 degreeC for 180 minutes, and obtained the high refractive index layer coating liquid 1.

The refractive index of the single layer produced using the high refractive index layer coating liquid 1 was 1.73.

<Formation of first reflective layer unit (3A)>
The coating liquid 1 for low refractive index layer and the coating liquid 1 for high refractive index layer prepared above were heated to 45° C. while keeping the temperature at 45° C. by using a slide hopper type coating device capable of simultaneously coating 32 layers. 5 layers of simultaneous multilayer coating (low refractive index) on a long base film 1 (polyethylene terephthalate film having a length of 1000 m and a thickness of 50 μm; manufactured by Toyobo Co., Ltd., Cosmoshine A4300, shown in FIG. 1 at 2A). Layers and high refractive index layers were alternately laminated to form 5 layers). At this time, the lowermost layer and the uppermost layer are low refractive index layers (108 nm), and other than that, the low refractive index layers (108 nm) and the high refractive index layers (96 nm) are alternately laminated to form five layers. The constituted 1st reflective layer unit (3A) was formed, and the 1st film unit 1 (F1) was produced.

The structure of the first reflective layer unit (3A) is as follows: substrate film 1/low refractive index layer (108)/high refractive index layer (96)/low refractive index (108)/high refractive index layer (96)/low refractive index The rate was set to (108). The numerical value in parentheses is the layer thickness (nm) after drying.

(Production of Second Film Unit 1 (F2))
Using the coating liquid 1 for forming a low refractive index layer and the coating liquid 1 for forming a high refractive index layer used for producing the first film unit 1, a second film unit 1 (F2) was produced according to the following method.

While keeping the low-refractive-index layer coating solution 1 and the high-refractive-index layer coating solution 1 used for the production of the first film unit 1 at 45° C. by using a slide hopper type coating apparatus capable of simultaneously coating 32 layers. , 21 layers on a long base film 2 (polyethylene terephthalate film having a length of 1000 m and a thickness of 50 μm; manufactured by Toyobo Co., Ltd., Cosmo Shine A4300, described as 2B in FIG. 1) heated to 45° C. Simultaneous multilayer coating (21 layers of low refractive index layers and high refractive index layers were alternately laminated) was performed. At this time, the lowermost layer and the uppermost layer are low refractive index layers (108 nm), and other than that, the low refractive index layers (108 nm) and the high refractive index layers (96 nm) are alternately laminated to form the 21 layers The constituted 2nd reflective layer unit (3B) was formed.

The configuration of the second reflective layer unit (3B) is as follows: substrate film 2/low refractive index layer (108)/high refractive index layer (96)/.../(Omitted)/.../low refractive index (108 )/High refractive index layer (96)/low refractive index (108), for a total of 21 layers. The numerical value in parentheses is the layer thickness (nm) after drying.

(Preparation of coating liquid 1 for forming an adhesive layer)
N-2147 (acrylic adhesive, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 100 parts by mass Tinuvin (registered trademark) 477 (ultraviolet absorber, manufactured by BASF Japan Ltd.)
2.1 parts by mass Coronate (registered trademark) HL (curing agent, manufactured by Tosoh Corporation) 5 parts by mass The above constituent materials are mixed and stirred at 50° C. for 1 hour to form an adhesive layer containing an acrylic pressure-sensitive adhesive. A coating liquid 1 was prepared.

(Production of light reflection film)
<Formation of Adhesive Layer 1 (AL) on Second Reflection Layer Unit (3B)>
While continuously transporting the produced second film unit 1 (F2), the layer thickness after drying the adhesive layer forming coating liquid 1 was 108 nm on the second reflective layer unit (3B) using a Clavier coater. The adhesive layer 1 (AL) was formed by coating and drying under the following conditions.

<Lamination of the first film unit 1 (F1) and the second film unit (F2) having the adhesive layer 1>
Then, according to the process flow shown in FIG. 5, the 1st film unit (F1) and the 2nd film unit (F2) which has the adhesive layer 1 (AL) were bonded, and the light reflection film 1 was produced.

The first reflective layer unit (3A) surface of the long first film unit (F1) and the adhesive layer (AL) surface of the long second film unit (F2) are opposed to each other and continuously conveyed, and have a diameter of A rubber pressure roller having a diameter of 5.1 cm (2 inches) and a metal heating roller having a diameter of 5.1 cm (2 inches) were passed through a roller gap to obtain a pressure of 5 N/cm and a temperature of 80° C. The light reflection film 1 was produced by laminating at a conveying speed of 1 m/min.

[Production of Light Reflecting Film 2]
In the production of the light reflection film 1, the light reflection film 2 was similarly prepared except that the number of layers (L1) of the first reflection layer unit (3A) of the first film unit (F1) was changed from 5 layers to 11 layers. Was produced.

[Production of Light Reflecting Film 3]
In the production of the light reflection film 1, the light reflection film 3 was similarly prepared except that the number of layers (L1) of the first reflection layer unit (3A) of the first film unit (F1) was changed from 5 layers to 21 layers. Was produced.

[Production of Light Reflecting Film 4]
In the production of the light reflection film 1, the light reflection film 4 was similarly prepared except that the number of layers (L1) of the first reflection layer unit (3A) of the first film unit (F1) was changed from 5 layers to 31 layers. Was produced.

[Production of Light Reflecting Film 5]
In the production of the light reflection film 1, the light reflection film 5 was similarly prepared except that the number of layers (L1) of the first reflection layer unit (3A) of the first film unit (F1) was changed from 5 layers to 33 layers. Was produced.

[Production of Light Reflecting Film 6]
According to the method described below, the light reflecting film 6 having the structure shown in FIG. 2 was produced.

(Preparation of first film unit 6 (F1))
Using a slide hopper type coating device capable of simultaneous coating of 32 layers, while keeping the low-refractive index layer coating liquid 1 and the high-refractive index layer coating liquid 1 used in the production of the light reflecting film 1 at 45° C., 11 layers simultaneously on a long substrate film 1 (polyethylene terephthalate film having a length of 1000 m and a thickness of 50 μm; Toyobo Co., Ltd., Cosmoshine A4300, described as 2A in FIG. 2) heated to 45° C. Multi-layer coating (11 layers of low refractive index layers and high refractive index layers were alternately laminated) was performed. At this time, the lowermost layer and the uppermost layer are low-refractive index layers, and other than that, the low-refractive index layers and the high-refractive index layers are alternately laminated to form a first reflective layer unit (11 layers) ( 3A) was formed.

Then, the adhesive layer-forming coating liquid 1 used in the production of the light reflecting film 1 was applied onto the first reflective layer unit (3A) by a clavia coater and dried under the condition that the layer thickness after drying was 108 nm. Then, the adhesive layer 1 (AL1) was formed.

Then, a second reflective layer unit (3B) composed of 11 layers was formed by the same method as that for forming the first reflective layer unit (3A).

(Production of Second Film Unit 6 (F2))
Using the coating liquid 1 for forming a low refractive index layer and the coating liquid 1 for forming a high refractive index layer used for producing the first film unit 1, a second film unit 6 (F2) was produced according to the following method.

While keeping the low-refractive-index layer coating solution 1 and the high-refractive-index layer coating solution 1 used for the production of the first film unit 1 at 45° C. by using a slide hopper type coating apparatus capable of simultaneously coating 32 layers. , 11 layers on a long base film 2 (polyethylene terephthalate film having a length of 1000 m and a thickness of 50 μm; manufactured by Toyobo Co., Ltd., Cosmoshine A4300, described as 2B in FIG. 1) heated to 45° C. Simultaneous multi-layer coating (11 layers of low refractive index layers and high refractive index layers were alternately laminated) was performed. At this time, the lowermost layer and the uppermost layer are low-refractive index layers (108 nm), and other than that, the low-refractive index layers (108 nm) and the high-refractive index layers (96 nm) are alternately laminated to form 11 layers. The constituted 3rd reflective layer unit (3C) was formed.

(Production of light reflection film)
<Formation of Adhesive Layer 2 (AL2) on Third Reflection Layer Unit (3C)>
While continuously transporting the second film unit 6 (F2) prepared above, a coating solution 1 for forming an adhesive layer, which is the acrylic adhesive, is dried on the third reflective layer unit (3C) using a Clavier coater. The adhesive layer 2 (AL2) was formed by coating and drying under the condition that the subsequent layer thickness was 108 nm.

<Lamination of the first film unit 1 (F1) and the second film unit (F2) having the adhesive layer 2>
Then, according to the process flow shown in FIG. 5, the 1st film unit (F1) and the 2nd film unit (F2) which has the adhesive layer 2 (AL2) were stuck together, and the light reflection film 6 was produced.

The surface of the second reflective layer unit (3B) of the long first film unit (F1) and the surface of the adhesive layer 2 (AL2) of the long second film unit (F2) are opposed to each other and continuously conveyed, and the diameter is increased. At a pressure of 5 N/cm at a temperature of 80° C. by passing it through a roller gap formed by a rubber pressure roller having a diameter of 5.1 cm (2 inches) and a metal heating roller having a diameter of 5.1 cm (2 inches). Then, the light-reflecting film 6 was produced by laminating at a conveying speed of 1 m/min.

[Production of Light Reflecting Film 7]
In the production of the light reflecting film 6, the number of layers (L2) of the second reflective layer unit (3B) constituting the first film unit (F1) is changed from 11 layers to 21 layers, and the second film unit (F2) is changed. A light reflecting film 7 was produced in the same manner except that the number of layers (L3) of the third reflecting layer unit (3C) constituting the layer was changed from 11 layers to 21 layers.

[Production of Light Reflecting Film 8]
In the production of the light reflection film 3, in the formation of the adhesive layer (AL), the coating liquid for forming the adhesive layer contains colloidal silica (Snowtex OXS, manufactured by Nissan Chemical Industries, Ltd. A light-reflecting film 8 was produced in the same manner except that the adhesive layer (AL) was formed, except that 10% by volume of average particle diameter: 4 to 6 nm) was added.

[Production of Light Reflecting Film 9]
A light reflecting film 9 was produced in the same manner as in the production of the light reflecting film 8 except that the addition amount of the inorganic fine particles in the adhesive layer (AL) was changed to 20% by volume.

[Production of Light Reflecting Film 10]
A light reflecting film 10 was produced in the same manner as in the production of the light reflecting film 8 except that the addition amount of the inorganic fine particles in the adhesive layer (AL) was changed to 22% by volume.

[Production of Light Reflecting Film 11]
A light reflecting film 11 was produced in the same manner as in the production of the light reflecting film 3 except that the layer thickness of the adhesive layer (AL) was changed to 540 nm.

[Production of Light Reflecting Film 12]
A light reflecting film 12 was produced in the same manner as in the production of the light reflecting film 3 except that the layer thickness of the adhesive layer (AL) was changed to 772 nm.

[Production of Light Reflecting Film 13]
A light reflecting film 13 was produced in the same manner as in the production of the light reflecting film 3 except that the layer thickness of the adhesive layer (AL) was changed to 980 nm.

[Production of Light Reflecting Film 14]
In the production of the light-reflecting film 3, the base film 1 (2A, PET) constituting the first film unit was changed to the following peelable transfer film (5) in the same manner as described in FIG. The light reflection film 14 having the structure was produced.

Transfer film (5): A release layer containing a silicone-based release agent is formed on the surface side of the polyethylene terephthalate film (thickness 50 μm) in contact with the first reflective layer unit (3A).

[Production of Light Reflecting Film 15]
According to the process flow shown in FIG. 4, the light reflection film 15 having the three reflection layer units shown in FIG. 2 was produced.

(1) Preparation of Second Film Unit (F2) Coating Liquid 1 for Low Refractive Index Layer and High Refractive Index Layer Used for Preparation of Light Reflecting Film 1 Using a Slide Hopper Coating Device Capable of Simultaneous Coating of 32 Layers While keeping the coating liquid 1 for application at 45°C, the long base film 2 heated to 45°C (polyethylene terephthalate film having a length of 1000 m and a thickness of 50 µm; manufactured by Toyobo Co., Ltd., Cosmo Shine A4300, Fig. 4). Was described as 2B.), 11 layers were simultaneously coated in layers (11 layers of a low refractive index layer and a high refractive index layer were alternately laminated). At this time, the lowermost layer and the uppermost layer are low-refractive index layers, and other than that, the low-refractive index layers and the high-refractive index layers are alternately laminated to form a third reflective layer unit (11 layers). 3C) was formed.

(2) Formation of Adhesive Layer 2 (AL2) While the above-prepared film unit is continuously transported, the adhesive layer that is the acrylic adhesive is formed on the third reflective layer unit (3C) using a Clavier coater. Adhesive layer 2 (AL2) was formed by applying and drying coating liquid 1 for the above conditions under the condition that the layer thickness after drying was 108 nm.

(3) Formation of Transfer Film/Second Reflective Layer Unit A second reflective layer unit was formed on the following transfer film (5) by the same method as described in (1) above.

Transfer film (5): A release layer containing a silicone-based release agent is formed on the surface side of the polyethylene terephthalate film (thickness 50 μm) in contact with the second reflective layer unit (3B).

(4) Base film 2/third reflective layer unit (3C)/adhesive layer 2 (AL2) produced in (2) and second reflective layer unit (3B)/transfer film (5) produced in (3) ) And (1) and (3) were assembled in the constitution shown in FIG.

(5) The transfer film (5) was peeled off from the unit formed in (4).

(6) and (7)
By the process shown in FIG. 5, the adhesive layer 1 (AL1) is formed on the second film unit (F2) and then bonded to the first film unit (F1) in the same manner as in the production of the light reflecting film 1. A light reflecting film 15 was produced.

[Production of Light Reflecting Film 16]
In the production of the light reflection film 3, the light reflection film 16 was produced in the same manner except that the constituent material of the adhesive layer (AL) was changed to the following polyvinyl alcohol adhesive instead of the acrylic adhesive. ..

<Preparation of polyvinyl alcohol adhesive>
A polyvinyl alcohol adhesive was prepared by adjusting an aqueous solution containing 20 parts by mass of methylolmelamine to a concentration of 0.5% by mass with respect to 100 parts by mass of an acetoacetyl group-modified polyvinyl alcohol resin (degree of acetylation: 13%). Was prepared.

[Production of Light Reflecting Film 17]
In the production of the light reflection film 3, the light reflection film 17 is produced in the same manner except that the constituent material of the adhesive layer (AL) is changed to the following ultraviolet curable acrylic adhesive instead of the acrylic adhesive. did.

In addition, the curing of the adhesive layer made of the ultraviolet curing acrylic adhesive is performed by the process flow shown in FIG. 5 by using the first film unit (F1) and the second film unit (F2) having the adhesive layer (AL). After pressure bonding and bonding, an irradiation device equipped with a gallium-encapsulated metal halide lamp as a UV irradiation light source (Fusion UV Systems, Inc. Light HAMMER10 valve: V valve, peak illuminance: 1600 mW/cm ² , integrated irradiation amount: 1000/mJ/ It was cured using cm ² (wavelength 380 to 440 nm).

<Preparation of UV-curable acrylic adhesive>
HEAA (hydroxyethylacrylamide) [manufactured by Kojin Co., Ltd.] 38.5 parts by mass Aronix M-220 (tripropylene glycol diacrylate) [manufactured by Toagosei Co., Ltd.] 20.0 parts by mass ACMO (acryloylmorpholine) [manufactured by Kojinsha] 38.5 parts by mass KAYACURE DETX-S (diethylthioxanthone) [manufactured by Nippon Kayaku Co., Ltd.]
1.5 parts by mass IRGACURE 907 (2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one) [manufactured by BASF] 1.5 parts by mass 50° C. by mixing the above constituent materials. And stirred for 1 hour to obtain an ultraviolet-curable adhesive.

[Production of Light Reflecting Film 18]
The light-reflecting film 3 was composed of only the first film unit composed of 21 layers, which was referred to as a light-reflecting film 18.

[Production of Light Reflecting Film 19]
In the structure described in the light reflecting film 3, the light reflecting film 19 was composed of only the first film unit having 42 layers.

[Production of Light Reflecting Film 20]
A light reflecting film 20 was produced in the same manner as in the production of the light reflecting film 3 except that the layer thickness of the adhesive layer (AL) was changed to 1.5 μm.

[Production of Light Reflecting Film 21]
A light reflecting film 21 was produced in the same manner as in the production of the light reflecting film 3 except that the layer thickness of the adhesive layer (AL) was changed to 3.0 μm.

Table I shows the main constitution of each of the light reflection films prepared above.

<<Evaluation of light reflection film>>
Each of the following evaluations was performed on each of the light reflection films prepared above.

[Evaluation of curl]
After cutting each of the light-reflecting films prepared above into 200 mm×200 mm, after putting them in a constant temperature and humidity chamber of 23° C. and 55% RH for 24 hours, they are placed on a smooth table under the environment of 23° C. and 55% RH. Then, the amount of lifting at the four corners was measured, and the average value was calculated and used as the curl amount.

[Evaluation of adhesion]
The adhesion is measured according to JIS K 5600, and the sample is scratched in a cross shape with a cutter, and a cut of 100 squares is made. After the cellophane tape was attached to the cut portion, it was pulled in the direction of 45° and the number of peeled masses was measured.

[Measurement of elastic modulus of tensile layer of adhesive layer]
The value of tensile elastic modulus was measured according to JIS K 7127 by the following method.

Each constituent material of the adhesive layer was diluted to a solid content concentration of 24% by mass, and applied and dried by an applicator so that a dry film thickness was 50 μm, to prepare an adhesive film.

The obtained adhesive film was cut into a size of 100 mm×10 mm to prepare a sample. This sample was pulled in the longitudinal direction of the sample using Tensilon RTC-1225A manufactured by Orientec Co., with a chuck distance of 50 mm, and the tensile elastic modulus was measured. The measurement was performed in an environment of 23° C. and 55% RH.

[Measurement of peak reflectance 1]
A spectrophotometer U-4100 (solid sample measurement system) manufactured by Hitachi was used to measure the reflectance in the wavelength range of 380 to 900 nm under the condition of 5° specular reflection to prepare a spectral reflectance histogram.

Next, the maximum reflectance peak in each histogram was determined, and this was designated as peak reflectance 1. 6 and 7 show representative spectral reflectance histograms.

[Measurement of full width at half maximum]
The full width at half maximum at the maximum reflectance peak of the spectral reflectance histogram created by the measurement of the above peak reflectance was determined.

[Evaluation of durability]
(Measurement of peak reflectance 2)
Each light reflection film produced above was subjected to forced deterioration for 500 hours in an environment of 85° C. and 85% RH, and then the peak reflectance 2 was measured in the same manner as above.

(Evaluation of appearance)
The light reflecting film subjected to the above-mentioned forced deterioration treatment was visually observed to confirm the occurrence of film peeling at the end.

The results obtained as described above are shown in Table II.

From the results shown in Table II, it can be seen that the light-reflecting film of the present invention is superior in curl, adhesiveness, optical characteristics (peak reflectance) and durability to the comparative examples.

1 Light Reflective Film 1A Laminated Body 2A Base Film 1
2B Base film 2
3A 1st reflective layer unit 3B 2nd reflective layer unit 3C 3rd reflective layer unit 5 Transfer film 6 Coater 7 Pressure roller 8 Metal heating roller 9 Ultraviolet irradiation light source AL Adhesive layer AL1 Adhesive layer 1
AL2 adhesive layer 2
F1 1st film unit F2 2nd film unit P Meeting point

Claims (6)

A light reflection film having a pair of base material films and two or more reflection layer units in which two or more layers having different refractive indexes are laminated,
An adhesive layer is provided between the two or more reflective layer units, and the layer thickness of the adhesive layer is within a range of 0.1 to 1.0 μm,
A light reflection film, wherein a reflection layer unit group composed of the two or more reflection layer units and an adhesive layer is sandwiched between the pair of base material films. In the configuration having the two or more reflective layer units, when the number of layers of one reflective layer unit facing each other with the adhesive layer in between is L1 and the number of layers of the other reflective layer unit is L2, each reflective layer unit The value L1/L2 of the ratio of the number of layers is within the range of 0.5 to 1.5, The light reflecting film according to claim 1. The light reflecting film according to claim 1 or 2, wherein one of the pair of base material films is a transfer film that can be peeled off. Content of the inorganic fine particle in the said adhesive layer is in the range of 0-20 volume%, The light reflection film as described in any one of Claim 1 to Claim 3 characterized by the above-mentioned. A method for producing a light-reflecting film for producing the light-reflecting film according to any one of claims 1 to 4,
A method for producing a light reflecting film, comprising using two or more film units having a reflecting layer unit on a base film, and bonding the two reflecting layer units via an adhesive layer. When bonding at least two film units, one film unit has a transfer film that can be peeled as a base film, and after peeling the transfer film, it is bonded to the other film unit via an adhesive layer. The method for producing a light-reflecting film according to claim 5, further comprising a step of combining.

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